The present invention relates generally to a composition exhibiting synergistic inhibition of the expression and/or activity of inducible cyclooxygenase-2 (COX-2). More particularly, the composition comprises, as a first component, a diterpene triepoxide lactone species and, as a second component, at least one member selected from the group consisting of a diterpene lactone species, and a triterpene species or derivatives thereof. The composition functions synergistically to inhibit the inducibility and/or activity of inducible cyclooxygenase (COX-2) with no significant effect on constitutive cyclooxygenase (COX-1).
Inflammatory diseases affect more than fifty million Americans. As a result of basic research in molecular and cellular immunology over the last ten to fifteen years, approaches to diagnosing, treating and preventing these immunologically-based diseases has been dramatically altered. One example of this is the discovery of an inducible form of the cyclooxygenase enzyme. Constitutive cyclooxygenase (COX), first purified in 1976 and cloned in 1988, functions in the synthesis of prostaglandins (PGs) from arachidonic acid(AA). Three years after its purification, an inducible enzyme with COX activity was identified and given the name COX-2, while constitutive COX was termed COX-1.
COX-2 gene expression is under the control of pro-inflammatory cytokines and growth factors. Thus, the inference is that COX-2 functions in both inflammation and control of cell growth. While COX-2 is inducible in many tissues, it is present constitutively in the brain and spinal cord, where it may function in nerve transmission for pain and fever. The two isoforms of COX are nearly identical in structure but have important differences in substrate and inhibitor selectivity and in their intracellular locations. Protective PGs, which preserve the integrity of the stomach lining and maintain normal renal function in a compromised kidney, are synthesized by COX-1. On the other hand, PGs synthesized by COX-2 in immune cells are central to the inflammatory process.
The discovery of COX-2 has made possible the design of drugs that reduce inflammation without removing the protective PGs in the stomach and kidney made by COX-1. These selective COX-2 inhibitors may not only be anti-inflammatory, but may also be actively beneficial in the prevention and treatment of colon cancer and Alzheimer""s disease.
An ideal formulation for the treatment of inflammation would inhibit the induction and activity of COX-2 without affecting the activity of COX-1. Historically, the non-steroidal and steroidal anti-inflammatory drugs used for treatment of inflammation lack the specificity of inhibiting COX-2 without affecting COX-1. Therefore, most anti-inflammatory drugs damage the gastrointestinal system when used for extended periods. Thus, new treatments for inflammation and inflammation-based diseases are urgently needed.
The natural pharmacopoeia of plants and herbs used in traditional medicines for the treatment of inflammatory conditions was recently found to contain COX-2 inhibitors. One such plant is Triptergium wilfordi (TW). This herb, known as Lei Gong Teng in China, has been used to treat patients suffering with rheumatoid arthritis with a 92% efficacy rate. Lei Gong Teng is available in the U.S. and is advertised to support the healthy functioning of bone joints (www.China-Med.net).
Over 60 compounds have been isolated from TW, and many have been identified as having anti-inflammatory and immunosuppressive activity. Representative compounds that have been isolated from TW include triptolide, 16-hydroxytriptolide, triptophenolide, tripdiolide, and celastrol. However, the administration and therapeutic effectiveness of these compounds have generally been limited by their low margins of safety.
Triptolide is one of the active, nonalkaloid principles isolated from TW and possesses an extensive suppressive effect on immune function, especially on T and B lymphocytes. Structurally, triptolide is a member of the group of diterpene triepoxide lactones (FIG. 1). The inhibitory effect is direct and believed to occur through the inhibition of interluken-2 (IL-2) production and IL-2R (receptor) expression (Tao, et al. (1995) J. Pharmacol. Exp. Therap. 272:1305; U.S. Pat. No. 5,500,340 to Lipsky et al. Mar. 19, 1996). Clinical trials show that it significantly inhibits the proliferation of peripheral blood mononuclear cells of rheumatic arthritis patients. After receiving this medication, patients usually indicate that stiffness, walking, and hand strength are improved with a decrease in inflammation index. Although not generally life-threatening, adverse effects of triptolide are relatively common in the clinical setting. Approximately 28% of patients taking this compound show some type of side effects, such as gastrointestinal disturbance, nausea and vomiting, hypotension and edema.
Therefore, while triptolide may be useful as an anti-inflammatory agent, it can be toxic even in clinically effective doses. Other researchers have used the triptolide molecule as a starting point for the synthesis of novel analogs expressing similar immune effects, while exhibiting lower toxicity (U.S. Pat. No. 5,962,516 to Qi et al. Oct. 5, 1999). Rather than modifying the triptolide molecule to achieve greater efficacy and lower toxicity, it is the object of this invention to combine triptolide, or a representative diterpene triepoxide lactone, with a second molecule to produce a synergistic effect in the target cell. One such synergistic response would be the inhibition of inducible COX-2.
Diterpene lactone species, such as andrographolide, and triterpene species, such as ursolic acid and oleanolic acid, are commonly found in plants and are used for their anti-inflammatory properties. The anti-inflammatory effects of these compounds have been described in the literature since 1960. Their mechanism of action is believed to be due (i) to the inhibition of histamine release from mast cells or (ii) to the inhibition of lipoxygenase and cyclooxygenase activity thereby reducing the synthesis of inflammatory factors produced during the arachidonic acid cascade. Since andrographolide and oleanolic acid have been found to promote the healing of stomach ulcers, it is unlikely that the cyclooxygenase activity that is inhibited is COX-1. In addition, andrographolide and oleanolic are potent antioxidants, capable of inhibiting the generation of reactive oxygen intermediates and restoring tissue glutathione levels following stress.
Combinations of botanicals containing triptolide, oleanolic acid along with other herbs have been use in both traditional and commercial medicine. However, the triptolide content of TW is only 0.1%, leaving 99.9% of the ingredients of TW as undefined. Such a large unknown fraction makes it extremely unlikely that triptolide is a significant factor in the pharmacological response of TW in this formulation. Thus, it would be useful to identify a compound that would specifically enhance the anti-inflammatory effect of triptolide so that it could be used at sufficiently low doses or at current clinical doses with no adverse side effects. The optimal formulation of triptolide for preserving the health of joint tissues, for treating arthritis or other inflammatory conditions has not yet been discovered. A formulation combining triptolide and a second compound to synergistically inhibit COX-2 and support the normalization of joint function has not yet been described or discovered.
While glucosamine is generally accepted as being effective and safe for treating osteoarthritis, medical intervention into the treatment of degenerative joint diseases is generally restricted to the alleviation of its acute symptoms. Medical doctors, generally utilize non-steroidal and steroidal anti-inflammatory drugs for treatment of osteoarthritis. These drugs, however, are not well-adapted for long-term therapy because they not only lack the ability to promote and protect cartilage, they can actually lead to degeneration of cartilage or reduction of its synthesis. Moreover, most non-steroidal, anti-inflammatory drugs damage the gastrointestinal system when used for extended periods. Thus, new treatments for arthritis are urgently needed.
The joint-protective properties of glucosamine would make it an attractive therapeutic agent for osteoarthritis except for two drawbacks: (i) the rate of response to glucosamine treatment is slower than for treatment with anti-inflammatory drugs, and (ii) glucosamine may fail to fulfill the expectation of degenerative remission. In studies comparing glucosamine with non-steroidal anti inflammatory agents, for example, a double-blinded study comparing 1500 mg glucosamine sulfate per day with 1200 mg ibuprofen, demonstrated that pain scores decreased faster during the first two weeks in the ibuprofen patients than in the glucosamine-treated patients. However, the reduction in pain scores continued throughout the trial period in patients receiving glucosamine and the difference between the two groups turned significantly in favor of glucosamine by week eight. Lopes Vaz, A., Double-blind clinical evaluation of the relative efficacy of ibuprofen and glucosamine sulphate in the management of osteoarthritis of the knee in outpatients, 8 Curr. Med Res Opin. 145-149 (1982). Thus, glucosamine may relieve the pain and inflammation of arthritis at a slower rate than the available anti-inflammatory drugs.
An ideal formulation for the normalization of cartilage metabolism or treatment of osteoarthritis would provide adequate chondroprotection with potent anti-inflammatory activity. The optimal dietary supplement for osteoarthritis should enhance the general joint rebuilding qualities offered by glucosamine and attenuate the inflammatory response without introducing any harmful side effects. It should be inexpensively manufactured and comply with all governmental regulations.
However, the currently available glucosamine formulations have not been formulated to optimally attack and alleviate the underlying causes of osteoarthritis and rheumatoid arthritis. Moreover, as with many commercially-available herbal and dietary supplements, the available formulations do not have a history of usage, nor controlled clinical testing, which might ensure their safety and efficacy.
It would be useful to identify a compound that would specifically and synergistically enhance the anti-inflammatory effect of triptolide so that these could be used at sufficiently low doses or at current clinical doses with no adverse side effects.
The present invention provides a composition comprising, as a first component, a diterpene triepoxide lactone species and a second compound that would specifically and synergistically enhance the anti-inflammatory effect of the diterpene triepoxide lactone. The composition comprises a diterpene triepoxide lactone species and at least one member selected from the group consisting of an active diterpene lactone species, and a triterpene species or derivatives thereof. Any diterpene triepoxide lactone, diterpene lactone or triterpene species is inclusive of derivatives of the respective genus. However, additional species or mixtures of species within the various genera may be present in the composition which is limited in scope only by the combinations of species within the various genera that exhibit the claimed synergistic functionality. The composition functions synergistically to inhibit the inducibility and/or activity of COX-2 with little or no effect on COX-1.
The present invention further provides a composition of matter to increase the rate at which glucosamine or chondrotin sulfate function to normalize joint movement or reduce the symptoms of osteoarthritis.
One specific embodiment of the present invention is a composition comprising an effective amount of triptolide and at least one compound selected from the group consisting of andrographolide, ursolic acid and oleanolic acid.
The present invention also provides a method of dietary supplementation and a method of treating inflammation or inflammation-based diseases in a warm-blooded animal which comprises providing to the animal suffering symptoms of inflammation the composition of the present invention containing a second component which specifically and synergistically enhances the anti-inflammatory effect of diterpene triepoxide lactone and continuing to administer such a dietary supplementation of the composition until said symptoms are eliminated or reduced.